In the same year that Randall and Sundrum published their model, Goldberger and Wise published a dynamical mechanism for stabilizing the model's extra dimension [1]}, [2]}. Their mechanism shares conceptual similarities with the standard technique of generating massive gauge bosons by spontaneously breaking the associated underlying gauge symmetry, wherein dynamics producing a non-zero vacuum expectation value (VEV) for a gauge-variant operator induces mixing between the longitudinal components of the gauge bosons with Goldstone bosons. In the Goldberger-Wise (GW) mechanism, a new 5D bulk scalar field \(\hat{\Phi }(x,y)\)  is appended to the RS1 model and included in new potential terms that also involve (via standard gravitational factors) the usual RS1 metric fields. That bulk scalar field then spontaneously acquires a background profile \(\phi _{0}(y)\)  with nonconstant dependence on the extra-dimensional coordinate \(y\) , causing mixing between background fluctuations \(\hat{f}\)  of the bulk scalar field and scalar fluctuations \(\hat{r}\)  of the RS1 metric. While this could in principle yield two physically-relevant superpositions of the bulk scalar field and scalar metric fluctuations, one combination is automatically forced to vanish in unitary gauge, leaving just one physical 5D scalar field in the spectrum.
